Sprinkler heads with rotatable pop-up nozzles propelled by internal water pressure are presently in widespread use. These heads are capable of discharging relatively large volumes of water over large areas of land to be irrigated. Many types of self-propelled rotatable sprinklers are known to the art.
One type of irrigation sprinkler, for example, includes a pop-up assembly which is caused to extend up through the cap of the housing against internal spring force by internal water pressure. The pop-up assembly is driven by an internal water-powered motor to turn back and forth over a pre-set arc. A nozzle is mounted on the upper end of the poppet assembly to be turned through the pre-set arc in order to irrigate a sector of the land being watered. This particular type of irrigation sprinkler is described, for example, in U.S. Pat. No. 4,650,118 which is assigned to the present Assignee.
The present invention is concerned with a sprinkler which may be similar to the sprinkler described in the preceding paragraph, or other type, which has been modified to render it effectively proof against damage due to forceable turning of the poppet assembly with respect to the housing, by vandals or others.
The sprinkler described in U.S. Pat. No. 4,650,118 is constructed so that when the pop-up assembly is turned by the internal water-powered motor in a first direction to one end of a preset arc, a trip tab on the pop-up assembly engages a shifter and moves the shifter a small angular increment. This movement of the shifter causes the internal mechanism of the sprinkler to reverse so that the pop-up assembly is then rotated in the opposite direction to the other end of its preset arc at which a second trip tab engages the shifter to cause the pop-up assembly to reverse and again turn in its first direction.
A problem encountered in irrigation sprinklers of the type described above, is that should the pop-up assembly be forced past its trip points, either by vandals or by others, there is a tendency for the trip tabs to break.
A feature of the irrigation sprinkler of the present invention is that the sprinkler is constructed so that should the turning assembly be forceably turned past the trip point in either direction, an axially resilient member on the shifter will be depressed before the engaging trip tab breaks. The drive of the sprinkler then forces the trip tab up and over the resilient member, and when the tab has passed the member, the member will return to its original position without damage. The turning assembly will then be driven over the resilient member of the shifter is shaped so that the tab will pass over it without moving the shifter. Accordingly, the sprinkler will automatically reset to its original arc of coverage.